FEMA correspondence regarding historic building cleaning treatments, March 2002

NYC 9/11 Public Portal Document

MAR. 15. 2002 1 1 :23AM NO, 792 P. 25

Cleaning Methods and Materials: The identification of • type of soiling, dust, dirt, or debris and specific building materials (e.g. stone, cast stone, concrete, brick, terra cotta) is necessary in order to determine appropriate building cleaning programs. St one- Gentle water cleaning, and gentle water cleaning with a detergent, is appropriate. Mild acidic and alkaline chemical leaning can be carefully considered for use based on material appropriateness if detergents are not effective. • Air abrasive cle y oar be appropriate if abrasive grit types are carefully considered and tested, Cast Stone- Ge'n'tle water cleaning and gentle water cleaning with a detergent is appropriate.

Brick- Gentle water cleaning, and gentle water cleaning with a detergent, is ,appropriate. Acidic and alkaline chemical cleaning can be considered for when detergents are not effective. Acidic and strong alkaline cleaning unglazed brick should not be used on glazed brick. Abrasive cleaning canchemical cleaning solutions surfaces. potentially damage brick

erra Cotta- Terra cotta should not be abrasively cleaned, or cleaned with acidic or strong alkaline cleaning solutions as these methods can damage glazes. Water cleaning, or water cleaning in combination with a detergent, is appropriate.

j • •' Health, Safety, and Environmental Issues: 'It is the responsibility of the Applicant to obtain all local, federal and state permits prior to the commencement of work and adhere to all Iocal, - state and federal laws with respect to. the application and disposal of potential hazardous waste materials.

Sources: -AIC Ethics and Standards Committee. "AIC Code 9f Ethics and Guidelines for Practice." Revised August, 1994.

Grimmer, Anne E. "Dangers of Abrasive Cleaning to Historic Buildings." Preservation Brief Number 6. Washington, DC: National Park Service, 1979.

New York Landmarks Conservancy. Historic Building Facades.' The Manualfor Maintenance and Rehabilitation. New Yorki John Wiley & Sons, Inc., 1997. - Weaver, Martin E. "Removing Graffiti from Historic Masoruy." Preservation Brief Number, 38. Washington, DC: National Park Service, 1995.

Note, National Park Service Preservation Briefs, including those references in these performance, standards, are available on the Internet; Keyword Preservation Briefs.

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NYC-WTC 000094067